Method of charging gas-expansion chambers of ice molds



METHOD (PF-CHARGING GAS-EXPANSION CHAMBERS 0F 10 E MOLDS L. L. I MALLARD Filed April 8, 1942 Patented Aug. 5, 1947 METHOD OF CHARGING GAS-EXPANSION CHAMBERS or ICE MOLDS Logan L. Mallard, Norfolk, Va.

Application April 8, 1942, Serial No. 438,180

This invention relates to refrigeration, and par- 6 Claims. (Cl. 226-20) ticularly to the production of frozen or congealed substances in the freezing compartment of a refrigerator, either domestic or commercial.

Specifically, the present invention is concerned with the charging of the gas expansion chambers of ice molds or trays such as disclosed in my copending applications Ser. No. 290,479, filed August 16, 1939, and Ser. No. 421,641, filed December 4, 1941, now Patent Number 2,377,436, dated June 5, 1945. In these molds or trays, the ice cell or mold proper is provided with a flexible or movabl bottom or diaphragm which is subjected to the expansion pressure of a gaseous medium when the tray is removed from its freezing chamber and exposed to room or atmospheric temperature; and when the tray is returned to its freezing chamber or compartment the gas contracts or becomes denser, permitting the flexible bottom or diaphragm to move downwardly ready to eject or dislodge the ice cube or block when the tray is again removed from its freezing chamber.

In charging the gas expansion chambers of these molds, it is desirable that the range or coefficient of expansion of the charge be such as to provide the necessary pressure while at the same time rendering the tray fool proof against rupture or explosion, irrespective of the temperatures to which the tray may be subjected while in use. Thus, for example, a housewife may plac the tray in boiling water to sterilize the same, or :in a commercial ice plant the molds may be ex- ;posed to extremely high temperatures during warm weather.

An object of the present invention therefore is to provide a method of charging the gas expan- :sion chamber of an ice mold whereby the charge 'will have a predetermined range of expansion irirespective of the temperatures encountered by the .mold in service, thus rendering the mold proof :against rupture due to excessive gas pressures and .safe in handling.

Generally stated, the method consists in charging the expansion chamber of a mold with a gas or a mixture of gases having'a known boiling point, subjecting the mold so charged to a temperature within the region of thehighest temperatures encountered by a mold of this type during service, adjusting the gas pressure as by bleeding the gas from the chamber until a safe operating pressure is obtained having a constant ex ipansion value, and then sealing the chamber.

A type of apparatus suitable for carrying out the method is illustrated in the accompanying :drawings, in which:

Figure 1 is a view in section and elevation of an expansion chamber type ice mold and apparatus for charging said chamber;

Fig. 2 is a transverse vertical section through the mold of Fig. 1 and a heating tank for heating and expanding the gas to a predetermined charging pressure; and

Fig. 3 illustrates the mold in section after it has been fully charged and sealed.

Referring to the drawings in detail, a single cell ice mold is generally indicated at It! and comprising a mold proper or cell I I having a flexible bottom or ejecting diaphragm l 2 and an outer shell [3 in which the cell II is seated and sealed around the upper marginal edges thereof, the said outer shell being spaced from the mold proper to provide an expansion chamber I 4.

It will be noted that the flexible bottom or diaphragm I2 is in its up position. This results from expansion pressure of the gases or gaseous medium in the chamber [4 and the force of this pressure should be sufficient to eject or dislodge an ice mass or block to be frozen in the cell II. The range of operating temperatures of certain gases suitable for charging the chamber need not necessarily be very great, since the ice in the tray tends to maintain the temperature while the tray is in the freezing chamber in the neighborhood of 32 degrees, and only a slight warming or rise in temperature may be necessary to cause the gases to expand sufficiently to move the diaphragm upwardly and dislodge or eject the ice block. The present method of charging places a definite limit to the expansion range, and this limit is never xceeded irrespective of the temperatures to which the mold may be subjected while in service. The shell is is bored or punctured to receive the one end of a charging nipple or tube l5 and a charge-adjusting or bleeding tube l6. To the charging nipple is connected the one end of a conduit I 1, said conduit being connected to a gas tank l8 provided with a pressure gauge I9. The conduit I1 is provided with a shut oif valve 20 and an adjusting valve 2|.

The tube l6 has connected thereto a bleeding conduit 22 provided with a gauge 23 and bleeding These tubes may be so constructed and arranged as to be scarcely noticeable and to impose little or no obstruction to the normal use of the tray.

The position in Fig. 1 illustrates the first step of the method, viz: the charging of the mold with a gas or blend of gases having a boiling point suitable for the type of mold to be charged. Any of the highly expansible gases may be used in charging the molds, assuming the boiling point of the gas is within the range of the freezing unit. A type of gas which has been used successfully for trays of domestic refrigerators is normal butane pure. An example of a blend of gases is commercial butane or propane, or a mixture of the two, assuming the composition is such as be varied or selected to meet conditions, without departing from the spirit or scope of the invention as defined by the appended claims.

What is claimed is:

1. In the art of refrigeration, the method of charging the expansion chamber of an ice mold having a movable ice dislodging member or diaphragm subject to the pressure of said chamber, which consists in first charging the chamber With a gas at normal pressure and density, heating the charge in said chamber, bleeding the gas from said chamber to adjust the upper pressure limit of its range of expansion, and sealing said chamto retain a boiling point sufiiciently high to come 7 Within the range of the average domestic freezing unit, Irrespective of what type of gas is used,- the boiling point should be calculated in accordance withthe freezing temperatures to which the tray is subjected. If the freezing temperature is 'quite low, such as infa commercial ice plant, then a relatively large selection of gases are'available. Also, it may bedesire'din'certain instances to have an extremely forceful or v'iole'n'tejecting action on the ice block when th'e mold is removed from its freezing chamber. Thus iii certain instances, the operating pressure need be only relatively slight or just sufiicient to-dislodge the ice block, or it may be increased to forcefully eject the block. fill'of 'thes'e factors should be taken into consideration in selecting theg'as forcharging theexpansion chamber. p

"The pressure or density of the-tank gas may be normal at room or atmospheric temperatures. This tank "or initial eharging gas may be purchased already bottled or 'seale'din tanks, or it may 'be manufact red on location.

The mold is then heate'd'as by placing it in a tank'25 havingtherinwater broughtto'a boiling temperature by heater 2 6,the temperature of the bath'being gauged'by'a'thermometer 21. As the temperature of the-gas charge rises and the-gas expands, the valve 24 is used to bleed the excess gas from the'chamber ld'until' the gage 23 shows that the:predetermined operating -pr'essure 'li 'a's been 'reached. The applied heat drives-outmondensed 'mois'ture or"dew from'the gas and places adefinite limit onthe range 'of expansion of the charge in-the chamber M. Thus let it be assumed that the gases are bledfrom the chamber [4 until the gage 23 shows 'a pressure of "approximately 20.nounds persquare'inch at a temperature'of-2l'2 'F. Let it further beassumed that whenthis charge-of dry gas is subjected to'a temperature of -F., for example, it will contract to apoint where thediaphragm l2 will move to its "down position, and when subjected to a temperature of 33951, for'example, it will expand sufiiciently to force the diaphragm to its up position and-dislodge an ice block'or mass from the cell 'll. Both the upper and lower limitsof the range of expansion are definitely fixed by the removal of volatile'matter or moisture from the charge in attaining-this range.

When the charge 'has been adjusted to the desired point'the tubes or nipples I5 and IE-are bent or deformed as indicated in Fig. 3, sealing the chamber Id.

The mold is now ready for use bearing acharge having a safe'pressure range.

fIt'will be'understood that the steps of the method maybe varied to attain the desired objects and also that theapparatus shown in the drawings is for illustrative purposes onl'y'arid may bar.

2, In the art of refrigeration, the method of charging the expansion chamber of an ice mold having a movable ice dislodging member or diaphragm subject to the pressure in said chamber, which consists in conducting a gas of normal density and pressure to said chamber, closing off the chamber from the 'source of supply, :heating the charge, bleeding the gas .from said chamber to obtain the upper pressure limit of its range of expansion, and sealin the charge in said chamber.

3. In the art of refrigeration, the method of charging the gas expansion chamber of an 'ice mold having a movable i'ceedislo'dging member or diaphragm subject to the pressure of 'the gas in saidcha'rnb'e'r, which consists in first charging said chamber'with'a gas having a predetermined boiling point at normal temperatures, heating the charge by subjecting the latter to a bath of fluid such as water'brought'tc apredeterm'ined temperature, and while the charge is 'being'heated, bleedin gas from said chamber until .the pressurein the chamber attains a predetermined point consistent with the operation of said icedislodging member, and then sealing the said chamber.

4. In the 'art of refrigeration, the method of charging the gas expansion chamber of 'an ice mold having amovab'le ice-dislodging member or diaphragm subject to, the .pressure in'sai'd chamber which consists in conductingto said chamber a charge of expansible gas 'at normal pressure and density "and having a known boiling point, closing off the chamber from its sourceofsupply and immersing "the mold in a vat or tank'of water, heating-the'water to a boiling temperature to heat the charge, bleeding the gas from said charge while the latter "is being heated until the charge attains a predeterminedpressure, and then sealing-the chamber.

5. The method of charging the'gas-expan'sion chamber of an ice mold having amovable'icedislodging wall portion, comprising providing "a supply of gas forcharging, providing a' linefrom said 5 supply to the chamber to he charged, "providing a separate discharge from said chamber, conducting-gas from thesource of supplytopass through 'sa-id line -'an'd chambertothereby"clear the line and chamber, shutting off discharge through said separate discharge from said :mold but retaining-the line from'the' mold tothe'source of supply open, subjecting th'e"mold.to"the "desired temperature and pressure to .provide gas of a desired density for operation of the mold under the desired conditions, 'an'd s'hutti'ng off;the supply "and discharge 'linesfro'm the'mold 'to obtain a predetermined .charge of expansible gas in the chamber and of a character to expand under certain conditions for removin 'icelfrom the mold.

6. 'The method of charging the expansion chamber of an ice mold having a movable icedislodging member or diaphragm movable by pressure in said chamber, said method comprising blowing gas from a supply tank through said chamber to discharge air therefrom, shutting off the discharge from said chamber while the chamher is in communication with the gas in the tank, subjecting said chamber to the desired temperature and pressure to determine the operation of the ice-dislodgin portion of the mold, and sealing the mold to contain the gas therein by sealing the connection between the mold and the gas tank and between the mold and the atmosphere.

LOGAN L. MALLARD.

REFERENCES CITED The following references are of record in the 5 file of this patent:

Number UNITED STATES PATENTS 

